1. Field of the Invention
Wind power installations with rotor blades of the most widely varying kinds have already long been known. It is also known that, in certain situations, the wind power installation has to be provided with a hazard light in order to draw the attention of air traffic in the region of the wind power installation to the existence of the installation, in good time. For the above-indicated purpose it is also known for the rotor blades to be provided with mostly red warning coats of paint so that it is possible to prevent an aircraft, in particular a military aircraft, from colliding with a wind power installation or the rotor thereof.
2. Description of the Related Art
The proposal has also already been put forward, for improving the warning to air traffic, to use incandescent lamps or other lighting means at the tips of the rotor blades, besides coloring the rotor blades with signalling colors, the lamps or lighting means then being switched on at night so that they can be readily seen by air traffic. The disadvantage of incandescent lamps or other lighting means however is that they are only of limited durability and the costs of replacing worn-out lighting means is not reasonably related to the benefit. Thus the costs of replacing lighting means at a rotor blade tip can be several thousand DM, because not only does the wind power installation have to be stopped, which is very expensive, but also the service personnel have to be lifted to the rotor blade tip by means of a crane arrangement from the pylon of the wind power installation or from the ground in front of the wind power installation.
That expenditure is grossly mismatched with the actual technical failure.
As a solution in this respect, it has therefore also already been proposed that the lighting device at the rotor blade tip may be of a redundant nature. However even such a concept cannot always ensure that the lighting arrangement does not suffer from failure, in which respect the reasons for failure of the lighting means may vary greatly, either that the lighting means at the rotor blade tip are mechanically damaged (hit by particles, hail, rain etc) or the respective electrical contacts are interrupted, or also other reasons.